Looking Up: The Swan flies with its own map’

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The State Journal-Register

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Posted Jul. 18, 2014 at 9:36 AM

Posted Jul. 18, 2014 at 9:36 AM

By Peter Becker

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One of the most prominent summer constellations is Cygnus the Swan. The graceful swan is a beautiful bird, and its counterpart among the stars is spectacular as well. The brighter stars form a distinct shape of a cross an is aptly nicknamed the Northern Cross. Cygnus is spread out overlapping the hazy Milky Way Band. Even if light pollution or summer haze takes away most of your view of the Milky Way, on a night without a Moon you are likely to be able to glimpse the Milky Way in this region.

In mid-northern latitudes, Cygnus the Swan rises high and passes overhead, far above the thicker haze along the horizon. The Milky Way will appear as a hazy shine right through the shape of the cross.

Deneb is the brightest star in the Swan, marking the top of the cross or when pictured as a swan, the birdís tail. On July evenings Cygnus will be seen in the east, with the cross shape on its side, and Deneb to the far left. To see the Northern Cross in an upright position, you must wait for it to pass into the western sky.

The star on the far opposite end marks either the bottom of the cross figure or the head of the swan. This is Albireo, and it is a wonderful double star. Even binoculars may resolve the two stars, if held very steady; a small telescope will split the pair easily into its blue and gold components.

If you have binoculars, sweep the Milky Way Band in this region and notice the richness of the star fields.

Within Cygnus are several examples of nebulae, vast cosmic clouds of dust and gas. Some are dark, obscuring background stars; others have a dim light of their own. A famous example of the latter is the so-called North American Nebula, which is not hard to imagine how it was named. The general outline shows a crude map of this continent. Next to it is the Pelican Nebula, which looks somewhat like the bird. This is the astronomical answer of laying on grassy hill and picking out shapes in the puffy clouds that cross a lazy summerís blue sky. Try it some day.

Conveniently, Cygnus the Swan migrates with its own celestial "map" of North America.

The North American and Pelican nebulae are found just north of the star Deneb. Binoculars or a small telescope can detect them on a very dark night.

To the south of Albireo is the bright star Altair, the eye of the constellation Aquilia the Eagle, discussed last week. On the opposite side of Albireo is the brilliant star Vega, in Lyra the Harp. The bright stars Deneb, Vega and Altair make a large triangle known simply as the Summer Triangle. On a dark night also look for the small and dim constellations Sagitta the Arrow and Delphinus the Dolphin. Both are marvelous in their compactness and configuration. Near Sagitta is another bright nebula, the Dumbbell, an amazing sight in even a small telescope- it looks like a puffy cotton ball, pinched in the middle. In Lyra the Harp is the famous Ring Nebula, in reach of a small telescope.